The present invention relates generally to an improved pump for transferring fragile or aggressive fluids, and more particularly to a pump comprising a housing enclosing an impeller, and wherein the housing component is disposable, and with the impeller component being designed for reuse. The present invention is a modification of the pumps disclosed and claimed in my U.S. Pat. Nos. 5,685,700, 5,924,848, 5,938,412, and 6,206,659, and each of which is assigned to the assignee of the present invention.
The pump structures of the present invention are designed to be bearing and seal-free, and with hydrodynamic forces supporting the impeller during operation. As such, these pumps are particularly well adapted for applications dealing with fragile fluids, including human or animal blood. Neither of these can tolerate exposure to forces such as unusual impact and/or sheer forces, and thus the advantages of utilizing bearing and seal-free pumps become apparent. Aggressive fluids include corrosive or poisonous fluids, as well as fluids which cannot tolerate contamination, or which otherwise may destroy seals and/or bearings to reduce the lifetime and/or longevity of the pump structure. Poisonous fluids, for example, are extremely dangerous when a leak develops, a common consequence of bearing failure. The pump of the present invention utilizes an impeller which is bearing and seal-free, being dynamically balanced during operation by a combination of hydrodynamic and buoyant forces. The pump of the present invention is particularly adapted for transferring human blood and is capable of creating a flow of such liquids without damaging and/or otherwise significantly adversely affecting the quality of the pumped fluid. Inasmuch as the impeller or rotor is reusable, it is economically sound practice to fabricate this component of materials which may either be costly, or alternatively, of materials which may present problems in fabrication due to their physical, chemical, and/or mechanical properties. Metals such as titanium and non-metals such as pyrolytic carbon and certain engineered plastics are examples of such materials.
Another feature of the impeller or rotor is that it be capable of receiving and reliably retaining electromagnetic components used in the drive system and capable of withstanding the cleaning operations, with such an array of permanent magnets being readily disposed within the rotor in a brushless motor configuration. Alternatively, permanent magnet-to-permanent magnet couplings may be employed and mounted in a similar fashion. Thus, the arrangement of the present invention provides for the economic utilization of a rotor which may be costly to fabricate initially, but because of its versatility and reusability, these rotors become highly economically viable.
In a typical application, any given assembly of the pump of the present invention and its associated structure is designed for single use only. In pumps of the present invention, following any given single use or application, the housing is separated into two or more parts, thereby freeing the rotor for subsequent cleaning and sterilization operations. Following the completion of the cleaning and sterilization operations, the rotor may be installed in a fresh housing. Housings of the present invention are provided with mating circumferential surfaces which are well adapted to be sealed together by means of adhesive and/or fusion bonding. The design of the pump of the present invention is such that housing tolerances are loose enough to provide for ease of assembly, with wide interchangeability of rotors being, of course, accommodated. Ease of reassembly is enhanced by virtue of the fact that the impeller or rotor is not attached physically to the housing.
In accordance with the present invention, a bearing and seal-free pump is provided comprising a housing which forms an operative enclosure about a hydrodynamically stable impeller or rotor. Means are provided for imparting rotational motion to the impeller, which is accordingly positioned within the chamber within the housing. Appropriate inlet and outlet ports are provided for accomplishing transfer of the fluid through the pump structure.
Therefore, it is a primary object of the present invention to provide an improved bearing and seal-free pump comprising a housing forming an enclosed pumping chamber in which a rotor is disposed. Being bearing and seal-free, relatively wide manufacturing tolerances may be accommodated, with the housing and rotor components being fabricated of appropriately selected materials. Inasmuch as the rotor is designed to be reusable, a wider variety of materials may be included in the list of suitable materials.
It is yet a further object of the present invention to provide an improved bearing and seal-free pump structure which has a configuration designed for ease of assembly and disassembly, thereby enhancing the utility of the system.
Other and further objects of the present invention will become apparent to those skilled in the art upon a study of the following specification, appended claims, and accompanying drawings.